Field of the Invention
The present invention relates to a floor panel which is used in a free access floor.
Description of the Conventional Art
The floor panel according to the present invention is used in the free access floor. The floor panel of the free access floor is provided above a foundation floor surface which is formed by a concrete material and constructs a part of a building construction, so as to be spaced (refer, for example, to patent document 1).
FIGS. 10 to 15 are views which are referred for describing a conventional floor panel 2. The conventional floor panel 2 constructs a free access floor 1 together with a support leg 4 which is provided in a rising manner on a foundation floor surface 3, as shown in FIG. 10.
The floor panel 2 is arranged on a horizontal surface having a height spaced above from the foundation floor surface 3 so as to be adjacent to each other in both vertical and horizontal axial directions as seen from the above, and four corner portions of the floor panel 2 are detachably supported to the support legs 4 which are provided in a rising manner on the foundation floor surface 3.
The floor panel 2 is constructed as shown by FIG. 12, by mainly combining a top plate 6 formed approximately as a plate shape so that an upper surface 6c is formed approximately as a square shape, and a bottom plate 8 formed as a box shape having a bottom surface 8c, vertically so that the upper surface 6c and the bottom surface 8c are opposed, as shown in FIG. 11. The top plate 6 and the bottom plate 8 are both constructed by using a steel plate member.
In the bottom plate 8 of the floor panel 2, as shown in FIG. 13, a side plate portion 8b folded approximately vertically toward an upper side in the drawing is formed from a peripheral edge portion of a bottom plate portion 8a, and a peripheral edge portion 8f folded toward a right side in the drawing is formed in an upper end portion of the side plate portion 8b. Accordingly, the top plate 8 is formed as a box shape having a concave space 8d which is formed in an inner side in a horizontal direction of the side plate portion 8b. 
Further, as shown in FIGS. 13 and 14, the peripheral edge portion 8f above the side plate portion 8b of the bottom plate 8 comes into contact with the peripheral edge portion 6f of the top plate 6, and the peripheral edge portion 6f and the peripheral edge portion 8f are joined to each other by welding or caulking.
As mentioned above, the floor panel 2 is formed as a hollow shape having an internal space 10 by integrally connecting the top plate 6 and the bottom plate 8. Further, the internal space 10 is provided with a reinforcing member 12 having a thickness.
Further, as shown in FIG. 11, the floor panel 2 is structured such that an opening portion 2a intruding approximately as a rectangular shape into an inner side is formed in one edge of side edge portions of the approximately square shape. The opening portion 2a is used for attaching a wall socket used for connecting an underfloor wiring to an office automation equipment installed on the floor panel 2, or simply passing the wiring thereto.
Further, as shown in FIGS. 14 and 15, a connection portion 6h and a step receiving surface 6g are formed in three edge portions which construct the opening portion 2a of the floor panel 2 and is formed approximately as a C-shaped form. A vertical cross section of the connection portion 6h is formed as a tapered shape, and the step receiving surface 6g extends horizontally and in a width direction from a lower end portion of the connection portion 6h and has a step in relation to the upper surface 6c. The step receiving surface 6g is formed along three edge portions which construct the opening portion 2a of the floor panel 2 and are formed approximately as the C-shaped form.
Further, three edge portions of a tabular lid member 18 are brought into contact with the step receiving surface 6g of the top plate 6 so as to close the opening portion 2a of the floor panel 2. The tabular lid member 18 is formed so that its upper surface is formed approximately as the same plane shape as the upper surface 6c of the top plate 6, as shown in FIG. 10.